16 year old water heater - suggestions?

[NeuroTypical]

So, our 16 yr old water heater has the temperature/pressure overflow thing trip about once a day, meaning it drains hot water out the overflow pipe.  It has done this for about a year or two.  This week's freak blizzard had an ice cap form over that overflow pipe, so the overflow thing sprang a leak and sprayed the wall.

Looking for info from knowledgeable people.  

1- Repair the overflow thing - it's cheap, and your water heater still has years of life on it!

2- Replace the water heater - new ones are better, you'll have to do it anyway.

3- Splurge and replace the heater with one of those cool "hot water on demand" things.  

If you think #1 isn't an option, what would #2 cost vs #3?  4 people/2 bathrooms in our house. 

[pam]

I'd go and just purchase a new one.  It's probably about time.

I bought a 40 gal electric one a few months ago at Home Depot.  Cost me close to $300 for it and all the parts needed.  But had to pay someone about $300 to replace it.  I have to do electric as I have no venting system for gas where it's placed.

[NeedleinA]

17 hours ago, NeuroTypical said:

2- Replace the water heater - new ones are better, you'll have to do it anyway.

^^^^ This is what I would personally do. 
This reminds me of taking showers on my mission. Most were cold water, but there was the occasional house with a "water heater", a little electronic device attached at the shower head. So yes, electricity and water... each morning was "Is today the day I'm going to get electrocuted?"

Not my picture, but pretty close. In finding this picture they sell more advanced looking ones for $100 if you are really daring

[Vort]

2 hours ago, NeedleinA said:

^^^^ This is what I would personally do. 
This reminds me of taking showers on my mission. Most were cold water, but there was the occasional house with a "water heater", a little electronic device attached at the shower head. So yes, electricity and water... each morning was "Is today the day I'm going to get electrocuted?"

Not my picture, but pretty close. In finding this picture they sell more advanced looking ones for $100 if you are really daring

I've run the math (back-of-the-envelope style) and concluded that you can't have a real in-line water heater if the water is room temperature. It simply draws waaaaay too much power. Like vastly too much.

Here's the math:

The typical US shower draws about 2.1 gallons per minute. Let's move to metric for ease of calculation. A bit over two gallons per minute is about eight liters per minute.

Let's also assume the water starts at room temperature (68° F, or 20° C) and that we want to heat it to 106° F (41° C). So we are heating the water up 21° C at a rate of one liter every 7.5 seconds.

A liter of water takes 1000 calories to heat up one degree. so we will need 21,000 calories (21 kcal). If you don't happen to remember the conversion of 4.182 joules per calorie, you can just Google "21 kcal to j" and find that you need to draw 87864 joules per 7.5 seconds, which is about 11,700 joules per second, i.e. 11,700 watts.

By comparison, the most power-hungry item in your house is probably your hair dryer, which probably does not burn more than 1500 watts. So you would need to draw the power of EIGHT HAIR DRYERS RUNNING SIMULTANEOUSLY to heat your shower water to shower temperature. You will need this for every shower in your house, and something similar for every place you want warm water to come out.

If power is voltage x current, then current is power / voltage, so you're drawing 11,700 watts / 115 V = over 100 amps every time you take a shower. Good luck getting your wiring and breaker box to accept such a load.

Edited April 20, 2016 by Vort

[NeedleinA]

34 minutes ago, Vort said:

I've run the math (back-of-the-envelope style)

That was your back-of-the-envelope math?? Please try harder next time Vort. Geez, my envelope math is more like: 2 ducks + 1 duck = 2.5 ducks
I hope everyone realizes I was joking about using those heads...

My showers in Chile and Costa Rica with those would last about 2 minutes max... the fear!

Edited April 20, 2016 by NeedleinA

[Guest]

16-year-olds can certainly be temperamental and uncooperative. 

[NeedleinA]

30 minutes ago, Eowyn said:

16-year-olds can certainly be temperamental and uncooperative. 

and they are ones who consume all the hot water anyways!

[NightSG]

2 hours ago, Vort said:

If power is voltage x current, then current is power / voltage, so you're drawing 11,700 watts / 115 V = over 100 amps every time you take a shower. Good luck getting your wiring and breaker box to accept such a load.

We install 18-27kW residential tankless heaters fairly often.  Yes, you'll need the wiring upgraded between the box and the heater, but I've only heard of having to upgrade the service when they were going in ancient houses that really needed an upgrade anyway.  Even then, the electrician is already doing a heavy wire run for the heater, so a 200A service upgrade at the same time isn't as expensive as you might think, and will save you having to do it later if you decide to install a double oven or some such.

This is the most popular "whole house" one we resell, at a bit under $500 for the unit itself: http://www.ecosmartus.com/products/electric-tankless/eco-11/#product-tab2

13kW point-of-use heaters are easier, and ideal for whole house service in places like mine, (I live alone, so nobody's washing dishes when I'm in the shower unless I take the dishes in with me, and there's nothing else using hot water but the shower and kitchen/bathroom sinks.  The rest of the time - 23 hours a day most days - a tank type heater is just keeping water hot for nothing.  If I cease to live alone, we'll just have to shower together so she doesn't get the urge to use hot water elsewhere.) but also fairly popular as a "post heat" for a specific point of use that needs hotter water than the rest of a regular system.  The remote is nice too, as you can just preset your shower temp, then not use cold water at all, and then dial up the heat later for your shave or to wash some grimy whites.

This is technically a whole house (more like "whole small apartment") unit, but most often used as a POU in larger houses at around $200: http://www.ecosmartus.com/products/electric-tankless/eco-11/#product-tab3

ETA: Not trying to sell you on these specific models; we really just offer them as a sideline to our solar sales, rather than as a real profit item.  You should be able to find them locally.

Edited April 20, 2016 by NightSG

[Vort]

Are there natural gas-powered versions of tankless water heaters? Electricity around here is cheap, around 10 cents per kWh or less, but if I were paying 25 cents or more per kWh, I would hate to think how much it would cost me to heat water on a yearly basis.

[LeSellers]

1 hour ago, Vort said:

Are there natural gas-powered versions of tankless water heaters?

Yes. Been around forever.

They require a stainless steel flue because the exhaust gasses are really, really, hot.

Lehi

Edited April 20, 2016 by LeSellers

[NightSG]

42 minutes ago, Vort said:

Are there natural gas-powered versions of tankless water heaters? Electricity around here is cheap, around 10 cents per kWh or less, but if I were paying 25 cents or more per kWh, I would hate to think how much it would cost me to heat water on a yearly basis.

Yes, but they're much more prone to buildup from hard water than the electric ones.  Most manufacturers won't warranty them without either an approved water softener or analysis of the water showing extremely low levels of calcium and other minerals.

Much easier to swap out elements in an electric than unclog the gas ones.

[Vort]

1 hour ago, LeSellers said:

The require a stainless steel exhaust flue because the exhaust gasses are really, really, hot.

That seeme like a design flaw. They should use a heat exchanger to capture the lost heat.

[LeSellers]

28 minutes ago, Vort said:

That seeme like a design flaw. They should use a heat exchanger to capture the lost heat.

Fluid engineering and heat exchange aren't my fortes. Since the whole point of on-demand water heat is energy savings, I imagine they'd have considered that. But, what do I know?

Lehi

[Vort]

25 minutes ago, LeSellers said:

Since the whole point of on-demand water heat is energy savings, I imagine they'd have considered that.

I am sure you're right. But the fact that you have super-hot exhaust seems to indicate otherwise.

[Guest]

10 hours ago, NeedleinA said:

^^^^ This is what I would personally do. 
This reminds me of taking showers on my mission. Most were cold water, but there was the occasional house with a "water heater", a little electronic device attached at the shower head. So yes, electricity and water... each morning was "Is today the day I'm going to get electrocuted?"

Not my picture, but pretty close. In finding this picture they sell more advanced looking ones for $100 if you are really daring

Oh my gosh, it has been a long time since I saw one of those.  How strange to have a feeling of nostalgia.

[Guest]

On 4/19/2016 at 2:37 PM, NeuroTypical said:

So, our 16 yr old water heater has the temperature/pressure overflow thing trip about once a day, meaning it drains hot water out the overflow pipe.  It has done this for about a year or two.  This week's freak blizzard had an ice cap form over that overflow pipe, so the overflow thing sprang a leak and sprayed the wall.

Looking for info from knowledgeable people.  

1- Repair the overflow thing - it's cheap, and your water heater still has years of life on it!

2- Replace the water heater - new ones are better, you'll have to do it anyway.

3- Splurge and replace the heater with one of those cool "hot water on demand" things.  

If you think #1 isn't an option, what would #2 cost vs #3?  4 people/2 bathrooms in our house. 

This isn't an engineering problem.  It's a plumbing issue.  A standard water heater should only last 5 to 10 years depending on the model.  The fact yours is 16 years old tells me you should buy a new one.

DO NOT WASTE MONEY ON A TANKLESS WATER HEATER!!!

In practice, they don't really save you any significant money. And they don't last much longer than traditional water heaters.  For the additional up front cost, they never pay for themselves.  It's a waste.  Don't do it.

The only real reason you'd want a tankless is if you just plain want the luxury.  Well, if you can afford it, then by all means go for it.

 

Edited April 21, 2016 by Guest

[ShannonPridemore]

You cab replace and install a new one.

[seashmore]

On 4/20/2016 at 10:08 AM, Vort said:

the most power-hungry item in your house is probably your hair dryer

I was under the impression it was your toaster.

[zil]

6 hours ago, seashmore said:

I was under the impression it was your toaster.

I bet my waffle iron could give the toaster a run for its money.

[zil]

Welcome, @ShannonPridemore!

[mirkwood]

I would get a new water heater and if you have room to jump up to 50 or 55 gallon do that.  I just replaced my 17 year old one a few months ago.

[zil]

Meanwhile, @NeuroTypical, after this little walk down memory lane, complete with members we no longer get to see, inquiring minds want to know: Is your water heater now 17, or has he been laid to rest and replaced by a hot young(er) thing?

[NeuroTypical]

Heh.  I ended up getting a new shiny one, and moved the location from the kitchen closet to the basement.  It's been humming away like a charm.  We used to have to wait 45 min from one shower/bath to the next, now it's under 30 minutes.

Happy camper, I.

[person0]

4 minutes ago, NeuroTypical said:

Heh.  I ended up getting a new shiny one, and moved the location from the kitchen closet to the basement.  It's been humming away like a charm.  We used to have to wait 45 min from one shower/bath to the next, now it's under 30 minutes.

How tiny of a water heater did you buy that you must wait 30 minutes between showers?  Even a small 40 gallon heater would be at least enough for 2 people.  I would recommend a low flow shower head.  That would stretch your hot water even further!

[NeuroTypical]

Well, I take long showers, and wife's large tub for hour long baths was almost a condition of her marrying me. 

(There are two reasons to take long showers.  Either you're too skinny, and have to run around trying to get the water to hit you.  Or you've got so much real estate to cover, it just takes a lot of water.  I ain't sayin' which applies here.)

Edited April 19, 2018 by NeuroTypical